Furnace-bridge-wall construction



F. A. HURLBUT.

FURNACE BRlDGE WALL CONSTRUCTION.

APPLICATION FILED JULY I3. 1918.

1,428,636. PatentedSept. 1.2, 1922.

2 SHEETS-SHEET l.

WITNESS; [NVEN TOR.

A TTORNE Y F. A, HURLBUT.

FURNACE BRIDGE WALL CONSTRUCTION.

AFPLiCATION HLED JULY 13.1-918.

& g PatemedSept. 12, 1922.

v HEET 2.

- 2 SHEETSS I u m 4% CZ & A TTORNE 1:

Patented Sept. 12, 1922..

cairn NT OFFICE.

FURNACE-BRIDGE-WALL CONSTRUCTION.

Application filed July 13,

T 0 all whom it may concern:

Be it known that I, FRANK A. HURLBUT, a citizen of the United States,residing at Flat River, in the county of St. Francis, State of Missouri,have invented certain new and useful Improvements in Furnace-BridgelVallConstruction, of which the following is a full and exact specification.

The present invention relates to improvements in the construction offurnace bridge walls, and while the improvements are useful with varioustypes of furnaces they are especially adapted for use in connection withboiler furnaces of the type fed by mechanical stokers. I

One of the principal objects in view is to provide an improved form ofbridge wall suspended in position overlying the rear end of the stokerand having no supporting connection with the main rear end wall of thefurnace stoker chamber.

Another object of the invention is to devise a bridge wallof thischaracter which will permit of maintaining a damper device, such asafforded by a door or gate construction, for regulating the amount ofopening which is left between the stoker and the lower edge of thebridge wall.

It is also an object to provide a damper device of the character justindicated which will be comparatively indestructible in its nature andalso adapted to have more or less of a self-adjusting action to conformto unevennesses in the material carried by the stoker grate. Provisionis also made for positively adjusting said damper device or gateconstruction to vary the amount of opening between the bridge wall andstoker as desired.

It is also sought to devise a constructio which will be not onlyefiicient forthe desired purpose, but also simple,-dur'able andeconomical, and comprising few parts which will be cheap to manufactureand to install.

With the above general objects in view, the invention will now bedescribed in detail with referenceto the accompanying drawingsillustrating one form of construction which has been devised forembodying the proposed improvements after which the novel featurestherein will be setforth. and defined in the appended claims.

. In the accompanying drawings Figurel is a vertical sectional view of1918. Serial No. 244,821.

a furnace, showing a bridge wall construction embodying the presentimprovements;

Figures 2, 3 and 4c are detail sectional v ews taken on the lines 2-2,83 and 4c-4, respectively, of Figure 1, but on a larger scale; and

.l lgure 5 1s a vertical section taken on the line 5-5 of Figure 3, andon a still larger scale.

The usual construction of bridge wall is to place the same approximatelyat the end of the grate or stoker and to support said wall by means ofthe main rear end wall of the furnace chamber which extends up from thefloor to the vicinity of the bottom'tubes of the boiler and is built inand forward to a certain extent so as to partly overhang the stoker.With such a construction, however, it has not been practical,heretofore, to maintaln any gate or damper arrangement for regulatlngthe size of the passage or opening between the stoker and bridge wall,which it is desired to maintain as small as possible while at the sametime allowing all the refuse from the furnace fire chamber to passthrough; the difiiculty being that with the bridge wall proper locatedat the rear of the stoker no gate or damper arrangement could bemaintained which could effectively withstand the action of the fire andnot be soon destroyed.

The present construction consists in suspending the bridge wall directlyover the stoker and entirely independent of any supporting connectionwith the rear end wall of the stolrer chamber. Referring to theaccompanying drawings in detail, these illustrate a mechanical stoker 6operating within the stoker chamber 8 of the furnace (see Fig. '1), therear end wall 10 ofsaid chamber 8 rising from the floor at the back edgeof'the ash pit 12. Ordinarily this wall 10 is built on up to the boiler14 and is also built inward towardthe front to form a bridgeor baffleportion jutting out partially over the rear end of'the stoker; but in myimproved construction the bridge wall proper is arranged, as shown at16, in suspended form,

overlying the rear end of the stolrer and independent of any support tobe derived from the rear end wall 10.

For protecting the lower margins of the suspended bridge 16 asmuch aspossible against the action of the fire of the furnace chamber, the sameis equipped with a water back member 18, which may be of any preferredform, that illustrated in the drawings being of the type shown in PatentNo. 1,269,083, issued to me June 11, 1918. Built into the wall 16 at therearof the water back 18 is an iron lintel 20 having its ends embeddedin the side walls 21 and 22 of the furnace and thus serving as a supportfor the masonry of which the bridge wall 16 is constructed; the lowerface of this lintel 20 is also formed with lugs 2 1- adapted to suspenda series of firebrick tile 26 (see Figure 4) on approximately a levelwith the water back 18 and in position directly overlying the stokergrate.

For regulating the amount or size of opening between the lower rearmargin of the bridge wall 16 and the stoker grate, a gate or damperconstruction is provided, as follows: A series of firebrick tilesections is suspended by means of a tubular member 32 of flattened ovalsection, which in turn is supported by a shaft 34: extendingtransversely over the stoker chamber 8 and between the side walls 21.and The opposite ends of the shaft 3% are provided with squared portionscarrying eccentrics 36, each supported on a pair of rollers carried byrocker arms 10 mounted on bracket pins 12 within boxes 4A; and 46 set inthe walls 21, and 22, respectively, at said opposite ends of the shaft341. The inner closure plate 48 of the box 46 is slidingly adjustablewithin the box and is clamped in proper position by means of a pair ofset screws 50. The closure plate -i8 and also the plate 52 of the box4-1 are provided with elongated openings 54; whereby the shaft 34: maybe raised and lowered by the action of the eccentrics 36 and at the sametime the tubular member 32 prevented from turning. Thus the tubularmember 32 and the tile sections 30 supported thereby are permitted onlyvertical movement; and in addition to the positive adjustment obtainedby means of the shaft and its eccentrics, the gate structure has also asel f-adjusting movement due to its being mounted loosely on said shaftthrough the medium of the tubular member 82, so that said gate structuremay automatically accommodate itself bodily to the material passingbeneath them on the stoker grate. A crank 56 is provided on the outerend of the shaft 3 1 (see Figure 3) or any equivalent means may beemployed for operating the shaft to set the eccentrics 36 and thusdetermine the lowest position of the tile sections to suit any givenconditions or requirements. It will also be observed, by reference toFigures 2 and 3, that the gate parts are so proportioned and arranged asto permit the same to be taken out through the box 46 and side wall. 22,whenever necessary for repair or renewal purposes, thus enabling anyattention of this nature to be given without interrupting the operationor service of the furnace or boiler.

An opening or observation door 60 may be provided in one of the sidewalls of the furnace at the rear of the bridge wall 16, so that air maycirculate at the back of the stoker and tend to lower the temperature atthe back of the bridge wall and gate structure, any aircirrulation atthe rear of the bridge wall 16 being of course immaterial, so far as thefurnace action is concerned, since the gate construction, together withthe passing refuse, constitute a seal to the fire chamber. In thepresent case also a cover plate structure 62 is arranged to span thespace between the suspension bridge wall 16 and the top of the rear endwall 10 of the stoker chamber 8.

A practical and efiicient construction is thus provided for carrying outthe desired objects of the invention. By mounting the bridge wall inadvance of the end wall. 10 and suspending said bridge wall entirelyseparate and independent of the end wall 10, as illustrated in Figure 1of the drawings, a bridge wall structure is obtained whereby not onlyall the functions and ad vantages of the usual form of bridge walls areretained, but in addition the improved construction is adapted for themaintaining of an effective gate or damper structure at the rear end ofthe stoker grate. The type of gate shown is adapted for self-adjustingmovement to accommodate itself to the thickness or unevennesses of thelayer of material carried by the grate and passing by underneath. Thismaterial before it reaches the gate is leveled andsmoothed ofii by thewater back 18 and the tiling 26; and the eccentrics are set so as topermit the gate to have a maximum drop to a level somewhat below thebottom face of said tiling, and. thus the gate is allowed to drag uponthe passing refuse material. The means shown and described. for raisingand lowering the gate enables the same to be readily adjusted forlimiting its maximum lowered position, as well as for raising it intofull-open position whenever desired. Again, the arrangement andconstruction are such as to withstand most efiectually the action of theheat which is of course very intense around the bridge wall opening,where all the parts provided. by the applicant are of {ire-clayconstruction, excepting the water back 18, this being awater-circulating member the principle of which will be readilyunderstood by reference to the patent above referred to.

lVhile I have illustrated and described what is now regarded as thepreferred formi of construction for embodying the proposed improvements,T desire to reserve the right to make such formal changes ormodifications as may fairly fall within the scope of the appendedclaims.

Having thus described the invention, what I claim is:

1. A furnace construction comprising a fire chamber having a progressivefeed stoker and a bridge wall overlying the rear end of said stoker, agate structure associated with the lower portion of said wall andcomprising a. transverse shaft having a gate member provided with abearing loosely mounted on said shaft, and eccentric supporting meansfor said shaft operating, on turning of the shaft, to raise and lowersaid gate member, the shape of said bearing being adapted to permitindependent selfadjusting movement of said gate member to accommodateitself to the material carried by the stoker.

2. A furnace construction comprising a fire chamber having a progressivefeed stoker and a bridge wall overlying the rear end of said stoker,agate structure associated with the lower portion of said wall andcomprising a transverse shaft having a gate member provided with abearing having a vertically elongated bearing passage accommodating saidshaft, whereby said member is permitted a limited degree of freevertical sliding movement relatively to said shaft.

8. A furnace construction comprising a fire chamber having a progressivefeed stoker and a bridge wall overlying the rear end of said stoker, agate structure associated with the lower portion of said wall andcomprising a transverse shaft having a gate member provided with abearing having a vertically elongated bearing passage accommodating saidshaft, whereby said member is permitted a limited degree of freevertical sliding movement relatively to said shaft, and means forrestricting said bearing to sliding movement in a vertical direction.

4. A furnace construction comprising a fire chamber having a progressivefeed stoker and a bridge Wall overlying the rear end of said 'stoker, agate structure associated with the lower portion of said Wall andcomprising a transverse shaft having a gate member provided with abearing having a vertically elongated bearing passage accommodating saidshaft, whereby said member is permitted a limited degree of freevertical sliding movement relatively to said shaft, and means foradjusting said shaft for varying the extent of downward sliding movementpermitted said bearing.

In witness WhGI'GOfI hereto affix my signature.

FRANK A. HURLBUT.

